In case a switch filter is just adding messages to those of a rank there's no need to use an Intercept message.

Sound switch

By sending a Program Change or Bank Select message, the sound device can be directed to switch to completely different sounds. Note however that this change effects subsequent key presses only (as specified in the wikipedia:Midi protocol).

An example setup to use Program change messages to shift the sound's program by 20:

If engaged, the filter will shift the sound's bank by 1. Note that the current program is resent after each Bank select, otherwise the latter will have no effect as specified in the wikipedia:Midi protocol.

Tremulant

When a switch filter is engaged, it can send messages that control the modulation of a sound device, e.g. a modulation controller message for a software synthesizer.

With every package of three messages the device is configured with the value 60 for LFO frequency (1), 1 for LFO to pitch (17) and 2 for LFO to volume (20). Note that we reset LFO to pitch and LFO to volume to 0 when the filter was disengaged.

Alternatively you could switch to different sounds which have their tremulant settings already applied. This gives the sound designer greater possibilities to fine-tune the sounds (in comparison to the rather limited capabilities of dynamic modulation).

If you want to switch between different tunings, you can use several switch filters. Note that only one of them should be engaged at a time and you should only use Engaged messages, otherwise their messages will interfere with each other.